Electron relay control system



Oct. 29, 1929.

E.G.DANELSON ELECTRON RELAY CONTROL SYSTEM Filed April 4. 1928 FI| 5 l /a /9 /a M 22 24 m /r gi F\ IN VEN TOR 5176 sf 6, Dan/e450 A TTORNEYS Patented a. 29, 1929 UNITED STATES ERNEST G. DANIELSON, 0]! SAN FRANCISCO, CALIFOB NIA ELECTRON RELAY CONTROL SYSTEM Application filed April 4,

This invention relates generally to electron relay systems of the cascade type, and is particularly applicable for adjusting the volume of response secured from the loud speaker of a radio receiving system.

It is an object of this invention to devise a system and method of controlling the intensity of current variation repeated in an electron relay system which utilizes at least one electron relay of the four element type.

:It is a further object'of this invention to devise a system and method of controlling the intensity of a repeated current variation in cascade electron relay systems, without causing distortion.

Further objects of the invention will appear from the following description in which I have set forth the preferred embodiment of my invention. It is to be understood that the appended claims are to be accorded a ran e of equivalents consistent with the state of t e prior art.

Figure 1 is a circuit diagram illustrating one specific embodiment of my invention.

Figure 2 is another circuit diagram illustrating a modification of my invention.

The system of my invention may be outlined briefly as'comprising an electron tube relay system for successively repeating our- 30 rent variations. At least one of the electron tube relays is of the four element type in which a fourth grid or element is connected to a source of potential independent of the curent variations for affecting the mutual conductance of the relay. Relays of this type having four elements have been dis-, 0

osed in the prior patents to Langmuir No. 1,558,487 and Schottky No. 1,537,708. In order to obtain a wide range of intensity of the repeated current variations, I utilize a combination of means for adjusting the potential applied to the fourth grid of the four element relay, and means for simultaneously varying the efliciency of a subsequent relay, these two means being adjustable by a common control.

- Referring to the drawings for a more complete description of the invention, I have shown a radio receiving system utilizing a plurality of electron relays connected to- 1928. Serial No. 267,270.

gether in cascade. Certain of these relays serve to amplify energy at radio frequency, and at least one relay serves to detect or integrate radio energy. In order to facilitate explanation of the invention I have shown only one rela 11 serving to ampli radio energy, and aving its ouput clrcult electrically associated with a subsequent relay 12 which preferably functions to detect or integrate t e radio ener The in ut of re- 00 lay 11 can be cascaded with a prece ing radio frequency amplifier 13, and the output of relay 12 can be repeated thru an audio frequency amplifier 14 of the electron relay type, before being impressed upon the loud speaker 15 or other suitable form of translator. Any suitable form of electrical coupling may be utilized .for associating together the successive stages of the system, as for example the tuned couplingtransformers 16. The input of amplifier 13 is associated with a source of radio signal energy such as the antenna 18, to which it is coupled thru a suitable tuned coupling device 19.

Relay 11 is shown as beingof the four ele- 7 ment type, having a fourth grid 21 in addition to the usual control id 22, cathode 23 and plate or anode 24. s reviousl explained relays of this type are isclosed 1n the prior patents to Langmuir No. 1,558,487 and so chottky No. 1,537 ,7 08. In practice the fourth grid 21 is connected to a source of positive potential independent of the current variations being repeated, and functions to increase the mutual conductance of the relay. I refer to employ a four element tube in WhlCh the grid 21 surrounds the plate '24 and shields the'same from the control grid 22 and cathode 23, thus preventing feed back of energy from the output to the input cir- 9o cult. A screen grid of this type is dlsclosed in the above mentioned Schottky patent.

Four element relays of the screen grid type are peculiar in that their repeating efliclency, or mutual conductance, cannot readily be adjusted merely by varying the plate otential. For example if the relay is adusted for optimum operation and it is attempted to control the intensity of repeated current variations by reducing the plate potential, the mutual conductance will not be reduced continuously res onsive to a reduction in the plate potentia but may increase as the plate potential'is being reduced thru certain values. In other words the characteristic curve of such a tube plotted against plate'potential, will-not show a gradual and continuous reduction in mutual conductance in response to a continuous reduction in plate potential. This characteristic of a four element relay makes it impractical to adjust the intensity of repeated current variations by inserting an adjustable resistance in the output or p ate circuit of the same. However. the mutual conductance of such four element relay can be adjusted uniformly by adjusting the positive potential applied to the fourth element or screen rid 21.

As one part of the combination of my system, I have therefore shown the screen grid 21 connected to a. suitable source of positive potential such as battery 26, in series withan adjustable or variable resistance 27. The ne ative terminal of battery 26 is connected'in the usual way to the cathode 23. Battery 25 together with battery 26 represents a source of plate potential for relay 11.

Resistance 27 is sufiiciently high that by adjusting the same, considerable variation of the positive potential upon the grid 21 can be produced with the result that the mutual conductance of the relay is adjusted over a substantial range.

As has previously been explained, my invention combines means for varying the mutual conductance of relay 11 with means for ad justing the efliciency of a succeeding relay. The adjusting of the efliciency of the succeeding relay is desirable since the insertion of the adjustable resistance 27 in the lead to screen grid 21, does not obtain sufiicient' range of volume control for all practical purposes. The subsequent rela which I simultaneously control is prefera ly the detector relay 12. This relay may be of any suitable type, and for convenience I have shown the usual three element relay comprising a control grid 31, cathode 32, and anode or plate 33. It is well known in the art that the efliciency of such a relay may be varied in a number of different ways. For example if negative grid bias rectification is employed, the efliciency may be varied by varying this bias, or the efliciency may be varied by varying the current supplied to the usual filamentary cathode or by varying the 'plate potential. I prefer however to vary the plate potential applied to relay 12, and for this purpose I have shown an adjustable resistance 34 connected in series with plate 33 and the source of plate potential, which for convenience has een shown as being the batteries 26.

The resistances 27 and 34 are made variable by a common control, and for this purpose I .variable' resistances 27 and 34, and which may be manually operated for example by a knob 37. Upon turning of knob 37, it will be apparent that either both resistances 27 and 34 will be decreased with the result that the potentials upon element 21 and upon the plate of relay 12 will be increased, or the potentials will be simultaneously decreased. In other words by means of my manual control, I simultaneously vary the mutual conductance of relay 11 by varying the potential upon the screen grid 21, and the repeating efiicieney of the detector tube 12. 'By means of this control, I am enabled to secure a Wide range of volume from the loud speaker 15 for a given si nal strength received from the antenna. l urthermore the increase or decrease in the volume is gradual and continuous for movement of the control member.

The system not only secures a wide range of volume control but this volume control is secured without distortion of the received signals, as the reduction in the mutual conductance of relay 11 prevents the detector relay 12 from being overloaded. If it were attempted to control the volume merely by adjusting the resistance 34 without adjusting the mutual conductance of relay 11 by varying the positive potential upon screen grid 21, then overloading of the detector relay 12 would cause distbrtion, due to the nature of the characteristic curve operated .upon. However by simultaneously controlling relay 11, in the manner explained above, overloading of detector relay 12 is prevented and the detecting and repeating action in this relay 7 always occurs upon that portion of the characteristic curve which will not cause distortion.

It is also characteristic of my system that I when the control is operated to reduce the volume of response to a given signal intensity,

the selectivity of the system is not impaired but is actually increased due to the decreased mutual conductance of relay 11. .This feature makes the system particularly valuable for radio broadcast receivers.

The system of Fig. 2 represents the preferred form of the invention, in which I dispense with the use of two variable resistances 27 and 34, and employ a single variable resistance 38 connected in series with both the grid of relay 11 and the plate of relay 12. By means of this arrangement, the system is materially simplified.

I claim:

1. In an electron tube relay system, a plurality of electron tube relays connected together in cascade for repeating current variations, one of said relays having a fourth element in addition to control grid, anode, and cathodeelements, said fourth element being connected to av source of potential, said one relay having a mutual conductance value dependent upon the potential on said fourth element, and means having a common control for efiecting a change in the repeating efliciency of a relay subsequent to said one relay and a change in the potential applied to said fourth element.

2. In an electron tube relay system, a plurality of electron tube relays connected together in cascade for repeating current variations, one of said relays having a fourth element in addition to control grid, anode, and cathode elements, said fourth element being connected to a source of positive potential, said one relay having a mutual conductance value which decreases upon a decrease in the positive potential applied to said fourth element, and means having a common manual control for effecting a decrease in the repeating efliciency of a relay subsequent to said one relay and a simultaneous decrease in the positive potential applied to said fourth element, or for effecting an increase in the repeating efficiency of said subsequent relay and simultaneously an increase in the positive potential applied to said fourth element. 1

3. In an electron tube relay system for reception of radio signal energy, a plurality of electron tube relays connected together in cascade, one of said relays serving to detect radio energy, another of said relays precedingsaid detecting relay having a fourth element in addition to control grid, anode and cathode elements, said fourth element being connected to a source of positive potential, said one relay In hand.

y ERNEST G. DANIELSON.

having a mutual conductance value which decreases upon a decrease in the positive poten-' tial and which increases upon an increase in said positive potential, and means having a common manual control for effecting a decrease in the repeating efiiciency of said de tector relay and a simultaneous decrease. in the positive potential applied to said fourth element, or for effecting an increase in the repeating eificienc of "said detector relay and a simultaneous increase in said positive potential applied to said fourth element.

4. In an electron tube relay system for reception of radio signal energy, a plurality of electron tube relays connected together in cascade, one of said relays serving to detect radio energy, another of said relays preceding said detecting relay having a fourth element in addition to control grid, anode and cathode ele ments, said fourth element being connected to a source of positive otential, said one relay having a mutual con uctance value which decreases upon a decrease in the positive potential and which increases upon an increase in said positive potential, and means having a common control for effecting a decrease in the plate potential'supplied to the anode of said detector relay and a simultaneous decrease in the positive potential applied to said fourth element, or for'eflz'ecting an increase in 

